For an in-cell touch screen, a touch system is integrated with a display screen, which results in a reduced thickness and a simplified production process. Therefore the in-cell touch screen is popular used. Generally, a liquid crystal display includes a color film substrate and an array substrate. On the array substrate, there are many circuit designs. For a common in-cell touch screen, the touch system is provided on the side of the color film substrate.
As shown in FIG. 1, a touch layer 100 is integrated on the side of the color film substrate of the in-cell touch screen. The touch layer 100 includes driving lines 101 and detecting lines 102 which are intersected with each other in both horizon and vertical directions. There is provided with an insulating layer (not shown in the figure) between the driving line 101 and the detecting line 102 such that a touch capacitor is formed between the driving line 101 and the detecting line 102. In order to ensure the touch function of the touch layer 100, the driving line 101 and the detecting line 102 need to be electrically tested so as to determine whether the driving line 101 or the detecting line 102 is opened or shorted.
Generally, a waveform judgment method is adopted to perform electrical testing on a touch layer. Specifically, a special electrical device is adopted to apply a driving voltage to the driving line 101, meanwhile a voltage waveform signal is collected from the detecting line 102, thus a determining result of whether the driving line 101 or the detecting line 102 is opened, shorted or closed can be judged according to collected voltage waveform signals. However, a special device for waveform collection is usually used as the aforementioned special electrical device, which needs a cooperation of a special computer and software, thus the cost is relatively high. In addition, all judgments are performed by comparing the collected waveform signals, thus a judgment rule is complicated, and a professional training needs to be performed on testing personnel. Moreover, because the aforementioned detection and judgment is an artificial one, even for professionally-trained testing personnel, there still has a relatively high risk of misjudgment, thus further resulting in a raised detection cost and a relative lowered detection accuracy rate.
Furthermore, another detection method of an in-cell touch screen often used in the art is a capacitance direct measuring method. Specifically, the capacitance between each driving line and the ground or between each detecting line and the ground is measured by a multimeter, and a judgment of whether the driving line or the detecting line is opened or shorted is made according to the measured capacitance values. Compared with the waveform judgment method, the capacitance direct measuring method neither needs to use an expensive special electrical device, nor has a complicated judgment rule. However, only the capacitance between one driving line and the ground or between one detecting line and the ground may be measured by each measurement of the capacitance direct measuring method, therefore it needs to spend relative long time to complete the measurement of a touch screen and the detection efficiency is very low, which may easily become the bottle neck of the capacity.